Charron-Bost and Schiper [1]} took a dual
approach to Gafni's work with the Heard-Of Model, by combining the concept of a fault
model where the only information is which
message arrives, from Santoro and Widmayer [2]}. Instead of specifying
communication by predicates on a set of suspected processes, they
used heard-of predicates: predicates on a collection of
heard-of sets, one for each round \(r\)  and each process \(j\) , containing
every process from which \(j\)  received the message sent in
round \(r\)  before the end of this same round.
This conceptual shift brings two advantages: a purely
abstract characterization of message-passing models
and the assumption of infinitely many rounds, thus of round termination.
